2026 ICD-10-CM Diagnosis Code I00Rheumatic fever without heart involvement

ICD-10-CM Codes›I00–I99›I00-I02›I00

ICD-10-CM I00
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I00 is a billable ICD-10-CM diagnosis code for rheumatic fever without heart involvement. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 545 through 547. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acute rheumatic heart disease and Bacterial infections.

Code Identity

ICD-10-CM Code
I00
Billable Status
Yes — Valid for Submission
Code Describes
Rheumatic fever without heart involvement
Chapter
I00-I02
Acute rheumatic fever

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI00-I02Acute rheumatic fever
CategoryI00Rheumatic fever without heart involvement
This CodeI00Rheumatic fever without heart involvement

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute rheumatic fever
  • Annular erythema
  • Erythema marginatum in acute rheumatic fever
  • Migratory polyarthritis
  • Recurrent rheumatic fever
  • Rheumatic arthritis
  • Rheumatic fever
  • Rheumatic fever without heart involvement
  • Rheumatic pneumonitis
  • Subacute arthritis
  • Subacute arthropathy
  • Subacute rheumatic arthritis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Includes

  • arthritis, rheumatic, acute or subacute

Type 1 Excludes

  • rheumatic fever with heart involvement I01.0 I01.9

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Erythema, erythematous(infectional) (inflammation)
      • marginatum
        • in (due to) acute rheumatic fever
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • rheumatic (active) (acute) (chronic) (subacute)
    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • in (due to)
        • rheumatic fever
    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • rheumatic
    • Rheumatic(acute) (subacute)
      • pneumonia

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR002
Acute rheumatic heart disease
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Rheumatic Fever

    a febrile disease occurring as a delayed sequela of infections with streptococcus pyogenes. it is characterized by multiple focal inflammatory lesions of the connective tissue structures, such as the heart, blood vessels, and joints (polyarthritis) and brain, and by the presence of aschoff bodies in the myocardium and skin.

Patient EducationClinical

Streptococcal Infections

Strep is short for Streptococcus, a type of bacteria. There are several types. Two of them cause most of the strep infections in people: group A and group B.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I00 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
390 Rheum fev w/o hrt involv
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I00Overview

Is I00 (Rheumatic fever without heart involvement) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report rheumatic fever without heart involvement on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I00 group to?

When rheumatic fever without heart involvement is the principal diagnosis on an inpatient stay, it groups to MS-DRG 545, 546, 547, with relative weights from 0.8362 to 2.4817 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I00?

Under the General Equivalence Mappings, rheumatic fever without heart involvement converts to ICD-9-CM 390 (rheum fev w/o hrt involv). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.